In conventional display-driving systems of this kind, use is made of two signals 180.degree. out of phase; this application of voltages of opposite polarities across the liquid-crystal display element results in a change in the visual appearance of that element either by the dynamic-scattering mode (DS mode) or by the elimination-of-twist mode in the polarization plane (TWIST mode), while application of voltage signals of like polarity across the display element restores the original appearance.